1. Field of the Invention
This invention relates to helicopter blades of the composite type which are characterized by the absence of a spanwise metal spar. More particularly the present invention relates to means for attaching tip weights to such a composite blade for the purpose of providing adjustable chordwise and spanwise balance of the blade.
2. Description of the Prior Art
Until recently helicopter blades have been made of metal and included a metal spar, often of airfoil contour, which extended throughout the length of the blade and frequently constituted the leading edge and main strength member of the blade, to which sheet metal box-like members were attached to complete the airfoil contour of the blade. Blade balance was obtained by bolting a metal tip block to the outboard end of the spar and attaching tip weights thereto. Access to the tip weights was provided by removing a tip cap attached along the chord by means of screws. A typical metal blade of this type is shown in U.S. Pat. No. 2,620,884, issued Dec. 9, 1952 to M. E. Gluhareff.
Bolted or screwed joints are not practical for an all-composite blade since their inefficiencies in this instance would require structural reinforcement resulting in undesirable weight penalty.